Electrical interrupter



May 11, 1954 F. MITCHELL ELECTRICAL INTERRUPTER 5 Sheets-Sheet 1 FiledJan. 3, 1952 y 1, 1954 F. MITCHELL I 2,678,361

ELECTRICAL INTERRUPTER Filed Jan. 3, 1952 5 Sheets-Sheet 2 3 MW @{LJ 43.

Patented May Il, 1954 2,678,361 ELECTRICAL INTERRUPTER Frank Mitchell,Adelaide, South Australia, Australia Application January 3, 1952, SerialNo. 264,745

Claims priority, application Australia March 29, 1951 9 Claims. (01.200-106) This invention relates to an improved electrical interrupter.

Interrupters and circuit breakers of many types have been proposedheretofore some of which were in the nature of a fuse which was blownwhen the safe current value was exceeded and some of which were in thenature of a switching mechanism actuated by a fault, overload or othercondition, the former type also including the cartridge type of fuse inwhich the arc is extinguished by a suitable surrounding liquid or solidmedium.

In the beforementioned cartridge type of fuse the interruption of thecurrent is achieved by a fusible element both for the liquid and thesolid material are extinguishing types. This factor limits the use ofthe cartridge to a specified minimum current so that some faults willnot be sufficient to actuate the fuse. The fuse is not usually operatedexcept by melting the fusible element.

It is therefore the principal object of this invention to provide acartridge type of interrupter with mechanical actuation initiated fromany type of fault on the system.

In the previously known forms of fuses or interrupters certaindifficulties have existed in breaking the circuit in a safe manner whichensures that the equipment protected by the fuse or interrupter suffersa minimum of damage and it has also been a problem to effectivelyoperate on multi-phase circuits of high operating voltages and currentsunless relatively expensive equipment was used.

In order to prevent unbalanced voltages from being impressed onmulti-phase consuming apparatus it is desirable with multi-phase systemsto interrupt all phases and a further object of this invention is tointerrupt all the phases practically simultaneously if a fault oroverload occurs on one or more phases.

A still further object of this invention is to provide a relativelysimple interrupter which, though it may be used on single-phaseinstallations, it particularly is appropriate for interrupting supply tomulti-phase equipment, this object being achieved by interposing thecurrent-interrupting member or members between insulators one at leastof which is movable under suitable control to effect the interruption.

In the case of multi-phase circuits the interrupting cartridges in allphases have their action initiated by suitably coupling the movableinsulators to effect the desired simultaneous interr ruption.

In accordance with this invention the improved electrical interrupterconsists of a plurality of insulators and a support for the insulatorsto allow relative movement between them. A cartridge which normallycarries the current but which may interrupt same is positioned betweenthe insulators and is actuated to interrupt when relative movementoccurs between the insulators. A control is provided to initiate theinsulator movement.

The cartridge may comprise loaded contacts locked by a withdrawable pindisposed to be displaced when movement occurs between insulators toallow the loaded contacts to part.

Relative movement between the insulators may take a number of forms andmay be effected in various Ways and while one insulator may be fixed,the other insulator when released may be permitted to fall through ashort distance. In the form illustrated the moving insulator is hingedand it is supported by an operating arm, and a trigger release isprovided for the operating arm so that an electrically operated tripcoil may release the operating arm to give the movement between theinsulators.

The cartridges used comprise mechanical current-interrupting meansdisposed in arc extinguishing means, the current-carrying means of thecartridge being mechanically opened when a force is applied between theends by relative movement between insulators. Throughout thisspecification the term cartridge is to be given this meaning.

Where the interrupter in accordance with this invention is applied to amulti-phase system each phase has a pair of insulators and the movementbetween the insulators in each phase is so utilised that it will actuatethe cartridges in all phases simultaneously. To give the requiredsimultaneous actuation of a cartridge in each phase, the one insulatormay be fixed for each phase and a hinged insulator provided for eachphase. The hinged insulators may be coupled together by a shaft which isprevented from turning by an operating arm restrained by a catch whichin turn is operated from an electri cally operated trip coil whichinitiates the movement between the insulators in each phasesimultaneously.

In order, however, that the invention may be more clearly understood itwill now be described with reference to the accompanying drawings inwhich:

Fig. 1 illustrates a front elevation of a threephase interrupter inaccordance with this init vention in which the operating parts for theinterrupter on one phase include the insulators and the cartridge butthe insulators and cartridges have been removed from the operatingsections of the other to illustrate the operation of the device.

2 is a side elevational section on line 2-2 of Fig. l and showing theinsulators and cartridge in position upon the operating section of theunit.

Fig. 3 is a section as on line Fl -3 of l and illustrates the operatingrods for both resetting the mechanism and earthing the terminals.

Fig. t is an enlarged sectional side elevation with the insulatorspartially broken away illustrating the actuating mechanism for theinterrupter.

Fig. 5 is a central sectional elevation illustrating one type ofcartridge which may be used in accordance with this invention, and

Fig. 6 is a partial central sectional elevation illustrating a furtherform of cartridge which may be used in accordance with this invention.

The drawings illustrate a three-phase system incorporating theinterrupter but it will be appreciated that the invention may be appliedto other inulti-phase systems or to a single phase line in a slightlymodified form.

The three phases have supports t, 5 and ii at the lower end of which arethe fixed lower sulators l which extend outwardl substantiallyhorizontally with a terminal contact 8 at their outer end to which maybe connected the line to ie interrupted.

The central support 5 has secured to it a mechanism box it having at itsforward end bearings for a phase coupling shaft i l which extendstransversely across the supports a, 5 and 8. The ends of the shaft iiturn in bearings upon the supports 4 and ii. Linked with the shaft H arethe movable insulator supports I2 which each have an upwardly extendingarm or bracket i l the upper end id of which is movable along a shaft 56secured to each of the supports 4, 5 and 6. Each shaft It has at itsforward end a stop I! and a spring I8 is positioned between the upperend ill of the arm I i the stop H. The downward movement of each uppermovable insulator H) which is secured upon the movable insulator support12 is therefore opposed by the action of the spring it which formsbuifer means and a limiting device for the downward movement of theinsulators it when. they turn with the phase coupling shaft II.

The control for the movement between the fixed insulators l and themovable insulators IQ for each phase is provided from the insulatorrelease box it which is carried upon the central support 5. Carried uponthe under side of the mechanism box H3 is a trip coil 20 having aplunger 2| which is arranged to be moved upwardly when the trip coil 26is energised. A trig-- ger 22 is pivoted at 23 to an operating arm 27and has a catch 25 adapted to restrain a reset arm 26 pivoted at therear of the mechanism box Ill. The reset arm '26 is positioned above theoperating arm 2"! which supports the central movable insulator support!2 by means of an adjustable stop 28. The outer pair of movableinsulator supports I 2 is coupled to the central support [2 by the shaftII. The trigger 22 is disposed in the path of the plunger 2i and thecatch 25 normally holds the reset arm 26 in position and thereforerestrains the operating arm 2'! which thereby supports the weight of themovable insulators It by means of the phase-coupling shaft ii. If afault or an overload occurs in the system a detecting relay energisesthe trip coil which will actuate the plunger 21 which will move upwardlyand operate the trigger 22 which in turn releases the catch 25 then thereset arm 26 and the operating arm 2? so that the insulators i9 may turndownwardly when the phase-coupling shaft ll rotates, it beingappreciated that the three insulators IS will move downwardlysimultaneously.

In. order to reset the catch 25 (as particularly illustrated in Fig. 3)the shaft 3!! upon which the reset arm 26 is secured has a lever arm 3|secured to it outside the mechanism box 10 and the free end of the leverarm M is coupled to a slotted clevis 32 secured upon the end of a resetrod 34.

To reset the unit after the plunger '21 has returned to its normalposition the reset rod 34 is simply moved downwardly which rotates thelever arm 3! and turns the shaft 3B which in turn will move the resetarm 26 downwardly to reset the catch 25 and move the operating arm 2'!into its normal position so that the movable insulators l9 will then belifted upwardly by the shaft ii in readiness for another trippingoperation. The reset rod 34' must be returned to its upper limit in theslotted clevis 32 after the resetting operation.

For each phase the movable insulator is has an upper contact 36incorporating an actuating head 31 and an actuating pin 38. Carried btween the actuating head 37 and the lower terminal contact 8 for eachphase is the current-interrupting cartridge 39, the cartridges beingeasily removable for replacement or renewal after the device has beenactuated to interrupt the circuit.

The type of current-interrupting cartridge 39 which may be used can bevaried according to re quirements but the cartridge particularlyillustrated in 5 is of the type having liquid arc extinguishing meansand may be actuated from the actuating pin 38 on the actuating head ti.

The lower end of the current interrupting cartridge 39 for each phase isconnected to the lower terminal contact 8 by a releasable clamp 40 whilethe top of the cartridge is connected to the actuating head 37 by meansof the releasable clamp 4!. The releasable clamp 41 is coupled to theactuating head 3'! by means of a clamping extension 42 and the link 43'so that the top or the cartridge 39 is held but will allow downwardmovement of the insulator IS. The releasable clamp ll is electricallyconnected to the upper contact 3i) by means of a braided connection.

The actuating pin 38 on the head 37 is normally retained above thesurface of the top of the current-interrupting cartridge 39 but when themovable insulator I9 is displaced downwardly when released by the tripcoil 20 the actuating pin 38 moves downwardly and strike a frangibledisc 44 positioned in the top of the current-interrupting cartridge 39.

With particular reference to Fig. 5a liquid type of current-interruptingcartridge is illustrated having an upper cap 45 and a lower cap ll;which are adapted to be carried by the releasable clamps 4i and 40respectively. Carried between the caps 45 and 46 is the insulating tube4? of glass. Disposed within the cap 45 of the cartridge is an annularcontact 48 which co-operates with a withdrawable contact 49 which isconical in form so that it give a line contact between it and theannular contact 48, The withdrawable contact 49 is itself spring-loadedto give the required pressure between the contacts to carry the current,the spring 56 being disposed within the tube 41. The conical end of thewithdrawable contact i9 is split at 5| and so shaped that this end cancollapse inwardly when a holding pin 52 is displaced from same. Theangle of the cone is selected to allow the spring 50 to exert therequired contacting force and also allow quick withdrawal of the contact49 from the fixed annular contact d8 when the holding pin 52 isdisplaced out of its locking position within the split portion of thewithdrawable contact Q9.

The holding pin 52 has its lower end enlarged in section and ispositioned within a reduced diameter section of the withdrawable contactMi but the other end of the holding pin 52 is adjacent the frangibledisc 44. It will be seen that with this arrangement using the frangibledisc 44 adjacent the holding pin i=2 the cap s5 is sealed at the sametime allowing the movement of the pin 52 when the frangible disc 44 isstruck by the actuating pin 38.

The tube ill is filled with a suitable arc-extinguishing fluid and theliquid director 53 is provided adjacent the withdrawable contact and insuch a position that when the holding pin 52 is displaced and thecontact is interrupted under the influence of the spring 50 a directflow of arcextinguishing fluid is directed to the site of the arc. Forthis purpose the director 53 has a lower conical face arranged to directa jet of liquid through the annular space between the inner opening ofthe member 53 and the periphery of the tube which it encircles.

The withdrawable contact 69 is provided with conducting tails 54 totransmit the current from it to the cap 46 at the lower end or thecartridge.

In actual operation when a fault occurs or it is desired to break thecircuit the movable insulators i9 for each phase are released from theirlocked position so that they fall downwardly to allow the actuating pin33 to strike the frangible disc 44 so that the holding pins 52 are moveddownwardly until the reduced section allows the expanded withdrawablecontact 69 to collapse and the spring pressure will cause the splitportion of the withdrawable contact $9 to be moved inwardly anddisplaced from its annular contact 58 so that the circuit isautomatically broken. At the same time for each phase it will beappreciated that when the circuit is broken and the arc occurs thearc-extinguishing material will automatically be thrown upwardly throughthe annular gap between the director 53 and the tube which it encircleto extinguish the arc.

One advantage of using this type of cartridge is that it is easilyreplaceable and it is only necessary to reload the cartridge to providea new frangible disc 44 and reseal same before the cartridge may beagain replaced between the upper and lower releasable clamps ll and torespectively.

Referring now to Fig. 6 a particular type of cartridge is illustratedwhich could be used in accordance with this invention and could beapplied between the insulator in a similar manner to the cartridgeillustrated in Fig. 5. The cartridge has a lower cap 56 and an upper capbetween which is the fibre tube 57 carrying the solid arc-extinguishingmaterial 58. The lower cap 55 has an annular contact 68 secured to itwhich co-operates with a withdrawable contact .8! the end of which isspecially shaped and is split so that its end can collapse inwardly whena holding pin 62 is withdrawn from its position in a reduced diameterportion of the withdrawable contact 6 l. The withdrawable contact 6| iscoupled to an upper terminal rod 63 which is spring actuated to displacethe withdrawable contact 6| from the annular contact 6%. An auxiliaryelement 64 may be provided in the form of an element or wire which maybe blown or broken when the upper terminal rod 53 moves upwardly whichinitiates the arcextinguishing means for lower current values while forlarger current values the actual breaking of the arc between the annularcontact 66 and the withdrawable contact 6! will initiate the vapourisingof the arc-extinguishing material 58.

It will be seen that the cartridge illustrated in Fig. 6 may be operatedin a similar manner to the type illustrated in Fig. 5 and that theholding pin 62 must be actuated by the relative movement betweeninsulator but is normally held at the lower end of the cartridge.Suitable coupling means may be applied from the upper movable insulator9 to achieve this purpose but it will be appreciated that the lowerinsulators l for each phase could be movable and the upper insulator i9could be fixed so that the lower terminal contact 8 could provide themovement to remove the holding pin 62 and actuate the cartridge.

In order to provide earthing of the lower terminal contact 8 and thupper contact 36, after the interrupter has operated, earthing blades 65and iii are provided for each phase which may be moved on to earthingcontacts carried by the contacts 36 and 8 to earth the whole device forremoval and replacement of the interrupting cartridge 39.

Although a particular feature of the interrupter is the fact that thecontrol to initiate the insulator movement is in the form of a tripcoil, it will be appreciated that the same mechanism could be actuatedmanually by mechanical tripping of the trigger.

From the foregoing it will be appreciated that an improved electricalinterrupter is provided which is characterised by a plurality ofinsulators at least one of which is movable but is normally held in afixed position, a self-contained electrical current-carrying cartridgebeing inserted between the insulators in such a manner that while theinsulators are in their locked position the cartridge serves as acurrent-carrying device but when, because of the operation of a faultdetecting relay or other device the one insulator is released to move toa new position such as by falling down under its own weight, means inthe cartridge itself are actuated to break the circuit between theinsulators although the cartridge will still remain as a bridge betweenthe insulators, but its capacity to carry current will have been removedbecause the which normally hold the contacts within the cartridge intheir current-carrying position will have been actuated to allow thespring means within the cartridge to have drawn the contacts apart andthe circuit will thus be broken.

In considering the invention it must be clearly borne in mind that theonly insulators used need be the standard types of supporting insulatorsfor switch gear which is being protected, one of which is allowed tomove so that the whole of the current-carrying means including thecartridge are fully supported on the two insulators, the movement of theone insulator being only slight as the actual break in the line iseffected by a mechanical breaker within the cartridge itself which ismerely initiated in its action by the slight movement of the movableinsulator.

I am aware that non-movable insulators have prior to this date supporteda cartridge in which a break is effected but a the insulators themselveswere non-movable it was necessary to carry through. one of theinsulators operating means which would have the full operating voltagimpressed across it.

I am also aware that insulators have had special breaking means insertedbetween them which themselves were supported on or by a further movableinsulator but in that case an additional insulator was required in whicha large movement was necessary so that the gear required of a relativelycomplicated nature as compared to my present invention. Also the largermovement necessary to effect the separation of the contacts makes highspeed operation impossible.

What I claim is:

1. An improved electrical interrupter characterised by a plurality ofinsulators, a support for the insulators to allow relative movementbetween the insulators, means to normally hold the insulators in a fixedposition, an electrical current-carrying cartridge between theinsulators, axially confined on one insulator, guide means between theother end of the cartridge and the other insulator, a trip coil toinitiate the insulator movement, a fixed contact in the car tridge, awithdrawable contact also in the car tridge having its one end split andbeing spring loaded, a holding pin in the split portion of thewithdrawable contact, means on the movable insulator to withdraw the pinwhen relative move ment occurs between insulators, and arc-extiinguishing material in the cartridge.

2. An improved electrical interrupter characterised by a fixed insulatorand a hinged insulator carried upon a support to allow movement of thehinged insulator, an operating arm to nor mally support the hingedinsulator in a fixed position, a trigger, a catch for the operating armreleasable by the trigger, an electrical currentcarrying cartridgebetween the insulators axially confined on the fixed insulator, guidemeans between the other end of the cartridge and the hinged insulator, apin in the cartridge to main tain the circuit, said pin beingdisplaceable by the said hinged insulator, arc-extinguishing means forthe cartridge, and an electrically operated trip coil to operate thetrigger release.

3. An improved electrical interrupter for multi-phase systemscharacterised by a fixed and a movable insulator for each phase, asupport upon which the fixed insulator for each phase is carried, atransverse phase-coupling shaft to which a movable insulator for eachphase is coupied and which shaft may be operated to simultaneously movethe insulators, an electrical current-carrying cartridge between thefixed and movable insulators for each phase, means in the cartridge tobreak the current between the insulators when the shaft is operated, anoperating arm coupled to the transverse phase-coupling shaft, a triggerto support the operating arm, a trigger release, and an electricallyoperated solenoid to operate the trigger release.

4. An improved electrical interrupter for a inulti-phase systemaccording to claim 3 in which said operating arm is restrained by areset arm coupled to a lever arm and reset rod, and the reset arm isheld by said trigger.

5. An improved electrical interrupter for a multi-phase systemcharacterised by a fixed and a movable insulator for each phase whichserve as terminals for current-carrying lines, a support upon which thefixed insulator for each phase is carried, a transverse phase-couplingshaft to which a movable insulator for each phase is coupled and whichshaft may be operated to simultaneously move the insulators, anelectrical currcnt-carrying cartridge between the fixed and movableinsulators for each phase secured to one insulator and guided by theother, an operating arm secured. to the transverse phase-coupling shaft,a trigger to support the operating arm, a catch for the operating armreleasable by the trigger, an electrically operated trip coil to operatethe trigger, an actuating pin on the movable insulator for each phase,and said cartridge for each phase comprising a fixed contact and awithdrawable spring loaded contact and a lockpin to normally hold thecontacts together, said locking pin being in the path of the saidactuating pin to move the locking pin to allow the contacts to disengageunder spring action when the movable insulator shaft is rocked.

6. An improved electrical interrupter according to claim 5 in which thewithdrawable contact is held in engagement with an annular surface onthe fixed contact by the said holding pin which has its one end held in.a split portion of the withdrawable contact and its other end in linewith the line of movement of the said actuating pin.

'1. An improved electrical interrupter for a multiphase systemcharacterised by a fixed and a movable insulator for each phase whichserve as terminals for current-carrying lines, a support upon which thefixed insulator for each phase is carried, a transverse phase-couplingshaft to which a movable insulator for each phase is connected and whichshaft may operate to simultaneously move the insulators, an electricalcurren carrying cartridge between the fixed and ovable insulators foreach phase secured to one ulator and guided by the other, an operatingcoupled with the transverse phase-coupling a trigger, a catch for theoperating arm releasable by the trigger, an electrically operated tripcoil to operate the trigger, an operating pin on the movable insulatorfor each phase, said cartridge for each phase comprising a fixed annularcontact, a withdrawable contact to fit therein, a holding pin to lockthe contacts together, and a spring to urge the contacts apart, saidcartridge being in the form of a cylinder having a frangible disc at oneend and having the holding pin held in a split portion of thewithdrawable contact, the cylinder containing an arcextinguishingliquid.

8. An improved electrical interrupter for a inulti-phase systemcharacterised by a fixed and a movable insulator for each phase, asupport upon which the fixed insulator for each phase is carried, atransverse phase-coupling shaft to which a movable insulator for eachphase is secured, which shaft may rock in bearings on the support, anelectrical current-carrying cartridge between the fixed and movableinsulators for each phase secured to one insulator and guided by theother, an operating arm coupled to the transverse phase-coupling shaft,a trigger to support the operating arm, a catch for the operating armreleasable by the trigger, an electrically operating solenoid to operatethe trigger, said cartridge for each phase comprising a fixed contact, awithdrawable contact to interrupt the flow of current, a holding pinheld in a split por-- tion of the withdrawable contact and actuated bydisplacement of the movable insulator, and the 9 cartridge containing asolid arc-extinguishing material.

9. An improved electrical interrupter for a multi-phase systemcharacterised by a fixed insulator for each phase, a transversephase-coupling shaft carried in hearings on a support, a movableinsulator secured to the shaft and extending outwardly for each phase toserve as a terminal for a current-carrying line, a current carryingcartridge between the fixed and movable insulators for each phasesecured to the said fixed insulator and guided by the said movableinsulator, releasable contacts in the said cartridge, spring means tourge the said contacts apart, a locking pin to normally hold the saidcontacts together, an operating connection between the said movableinsulator and the said pin, a mechanism box carried by a support for onephase,

an operating arm coupled to the shaft and carried in the mechanism box,an electrically operated trip coil carried by the mechanism box, aplunger actuated by the trip coil, a reset arm restraining the operatingarm, a catch restraining the reset arm and actuated by the plunger torelease the weight of the movable insulator, and spring loading tocontrol the striking force of the movable insulator for each phase.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,522,498 Conrad Jan. 13, 1925 1,937,409 Lemmon et al Nov. 28,1933 2,098,692 Pittman et al Nov. 9, 1937 2,331,221 Ortensi Oct. 5, 1943

